Conventional punching involves hitting a workpiece between a punch and a die, in such a way that the punch perforates the piece, and enters the die, creating a hole in said piece claim
If said hole is closed, i.e., is surrounded in its total lateral contour by material of the workpiece, forces and moment are balanced regarding the reaction forces distribution in the die. The punch only bears the punching force in the punching axis, but no appreciable moment is created, neither other forces are born by the punch.
However, sometimes holes are open, and they are called notches. Notching is a more difficult operation than conventional punching, as in these operations, forces and moment are not balanced. This lack of balance may produce some damage in the punch press internal parts, due to the high magnitude of reaction forces and the fact that punch presses are not adapted to bear such forces.